German Published Patent Application No. 38 42 790 and German Published Patent Application No. 39 02 537 describe key cases which accommodate a flat key that can be swung out. Moreover, German Published Patent Application No. 42 26 579 describes a compact transmitter for remote control of a locking device, which additionally includes a swing-out flat key for the mechanical operation of a lock cylinder.
German Published Patent Application No. 10 2005 043 893 describes a key tag, especially for vehicle keys, which includes switching elements and a display window.
German Published Patent Application No. 102 06 534 describes a vehicle key having an electronic key and a mechanical emergency key. The emergency key may be swiveled by a rotary motion from an idle position to a position of use.
European Published Patent Application No. 1 280 390 describes an electronic key having a two-part housing, which is able to accommodate a mechanical key part.